Atom-economic Reaction Research Articles

An atom-economic reaction for synthesis of 1-phenoxy-2-propanol over Al 2O 3/MgO

Al 2O 3/MgO materials with various Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analysis. These materials were used as catalysts for synthesis of 1-phenoxy-2-propanol (1-PhP) from phenol and propylene oxide as compared with some oxides, i.e. MgO, CaO, ZnO and Al 2O 3, etc. Al 2O 3/MgO with Al/Mg molar ratio of 1.5% exhibited outstanding catalytic performance with 98.2% conversion and 99.3% selectivity to 1-PhP at 120 °C for 5 h. This catalyst can be easily recovered and reused due to its heterogeneous catalytic nature.

ChemInform Abstract: Unique Catalytic Features of Ag Nanoclusters for Selective NOx Reduction and Green Chemical Reactions

AbstractReview: 129 refs.

ChemInform Abstract: Development of Atom‐Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

AbstractReview: 196 refs.

Efficient hydrogenation of organic carbonates, carbamates and formates indicates alternative routes to methanol based on CO2 and CO

Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate 'green' reactions. A possible mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core.

ChemInform Abstract: Highly Efficient Pd(acac)2/TFA Catalyzed Head‐to‐Tail Dimerization of Vinylarenes at Room Temperature.

AbstractTFA highly promotes the activity and selectivity of the process.

ChemInform Abstract: Efficient Carboazidation of Alkenes Using a Radical Desulfonylative Azide Transfer Process.

AbstractIn this paper a new class of reagents that allows an atom‐economical carboazidation reaction to be run under tin‐free conditions is prepared.

Physico-Chemical Properties of Non-Newtonian Shear Thickening Diisopropyl-ethylammonium-Based Protic Ionic Liquids and Their Mixtures with Water and Acetonitrile

New protic ionic liquids (PILs) based on the diisopropyl-ethylammonium cation have been synthesized through a simple and atom-economic neutralization reaction between the diisopropyl-ethylamine and selected carboxylic acid. Densities and rheological properties were then measured for two original diisopropyl-ethylammonium-based protic ionic liquids (heptanoate and octanoate) at 298.15 K and atmospheric pressure. The effect of the presence of water or acetonitrile on the measured values was also examined over the whole composition range at 298.15 K and atmospheric pressure. From these values, excess properties were calculated and correlated by using a Redlich−Kister-type equation. Finally, a qualitative analysis of the evolution of studied properties with the alkyl chain length of the anion and with the presence or not of water (or acetonitrile) was performed. From this analysis, it appears that selected PILs and their mixtures with water or acetonitrile have a non-Newtonian shear thickening behavior, and t...

Transition-Metal-Catalyzed C−S, C−Se, and C−Te Bond Formation via Cross-Coupling and Atom-Economic Addition Reactions

Transition-Metal-Catalyzed C−S, C−Se, and C−Te Bond Formation via Cross-Coupling and Atom-Economic Addition Reactions

Highly efficient Pd(acac)2/TFA catalyzed head-to-tail dimerization of vinylarenes at room temperature

Pd(acac)2 catalyzed dimerization of vinylarenes to form dimers under mild condition with excellent yields and stereoselectivities. In particular, the use of TFA highly promoted the activity and selectivity of the dimerization. The studies on mechanism for the reaction displayed clearly that the dimerization of styrenes is 100% atom economic reaction.

Intermolecular Hydroacylation of Homoallylic Sulfides

Asymmetric hydroacylations are extremely atom-economic reactions for the preparation of chiral ketones starting from alkenes and aldehydes. The intermolecular hydroacylation of terminal olefins usually gives the linear (achiral) products or mixtures of regioisomers. Herein, an intermolecular asymmetric and heteroatom-­directed rhodium-catalyzed hydroacylation between salicylaldehydes 1 and homoallylic sulfides 2 has been developed. The methodology allows the formation of α-branched isomers 3 in excellent regio- and enantioselectivities.

Development of Atom-Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

The development of atom-economical catalytic asymmetric reactions based on two distinct sets of catalyst, a rare earth metal/amide-based ligand catalyst and a soft Lewis acid/hard Brønsted base catalyst, is reviewed. These catalytic systems exhibit high catalytic activity and stereoselectivity by harnessing a cooperative catalysis through hydrogen bond/metal coordination and soft-soft interactions/hard-hard interactions, respectively. The effectiveness of these cooperative catalysts is clearly delineated by the high stereoselectivity in reactions with highly coordinative substrates, and the specific activation of otherwise low-reactive pronucleophiles under proton transfer conditions. The rare earth metal/amide-based ligand catalyst was successfully applied to catalytic asymmetric aminations, nitroaldol (Henry) reactions, Mannich-type reactions, and conjugate addition reactions, generating stereogenic tetrasubstituted centers. Catalytic asymmetric amination and anti-selective catalytic asymmetric nitroaldol reactions were successfully applied to the efficient enantioselective synthesis of therapeutic candidates, such as AS-3201 and the β(3)-adrenoreceptor agonist, showcasing the practical utility of the present protocols. The soft Lewis acid/hard Brønsted base cooperative catalyst was specifically developed for the chemoselective activation of soft Lewis basic allylic cyanides and thioamides, which are otherwise low-reactive pronucleophiles. The cooperative action of the catalyst allowed for efficient catalytic generation of active carbon nucleophiles in situ, which were integrated into subsequent enantioselective additions to carbonyl-type electrophiles.

Unique catalytic features of Ag nanoclusters for selective NOx reduction and green chemical reactions

The size control of Ag into nanoclusters generates unique catalytic features of Ag on automotive emission control and environmentally friendly organic reactions. Hydrogen-assisted selective catalytic reduction of NO by hydrocarbons (H2–HC–SCR), which is one of the promising technologies for removal of NO in the diesel engine exhausts, results in the formation of Ag clusters on alumina or zeolites and enhancement of the conversion of NO into N2. A mechanistic study using in situUV-Vis, EXAFS, and FT/IR revealed that the promotion of partial oxidation of hydrocarbons by active oxygen species is the essential role of Ag clusters. Hydrogen is suggested to be indispensable for the formation of the Ag cluster and the active oxygen. The important role of hydride on the formation of H2O2-like active chemical species on Ag clusters was confirmed by density functional theory (DFT) calculation. Knowing the high activity of Ag nanoclusters for the formation of Ag-hydride, supported Ag clusters were applied for various organic reactions. Supported Ag clusters on appropriate metal oxide, especially Al2O3, are recyclable and show very high activity and selectivity for atom-economic reactions, i.e., alcohol dehydrogenation, C–C coupling reaction of alcohols, direct amide synthesis from alcohols and amines, N-benzylation of anilines with alcohols, and selective hydrogenation of nitroaromatics.

ChemInform Abstract: Synthesis of Cyclic Carbonates from Epoxides and CO2

AbstractReview: 175 refs.

25 Years Full of Chemical Discovery

25 Years Full of Chemical Discovery

The Structure−Activity Relationship and Physicochemical Properties of Acetamide-Based Brønsted Acid Ionic Liquids

We prepared three series of novel protic ionic liquids (PILs) based on acetamide and a Bronsted acid (HX, where X is CF3COO−, CH3COO−, or HSO4−) by a simple atom-economic neutralization reaction. We investigated their physicochemical properties, such as acidic scale, viscosity, ionic conductivity, and thermal characteristics, as well as the structure−activity relationships of these PILs. Carboxylic acid formation is only observed in the acetamide sulfate complex system by FT-IR. The ionic conductivities for most of the samples are between 10−3 and 10−1 S/m at room temperature and at low viscosity. Acetamide trifluoroacetate (ATFA) with a molar ratio of 5/5 (acetamide/trifluoroacetic acid) has an ionic conductivity of 0.25 S/m, and its viscosity is only 10 cP at 25 °C. The samples exhibit better properties at higher temperatures. ATFA with molar ratios of 7/3 and 8/2 have ionic conductivities of 1.13 and 1.07 S/m at 80 °C, respectively. Moreover, most of the prepared samples possess relatively moderate the...

Synthesis of fluorescent hydroxyl naphthalene-1,4-dione derivatives by a three-component reaction in water

An efficient one-pot synthesis of fluorescent hydroxyl naphthalene-1,4-dione derivatives by a simple, atom-economical and three-component reaction of 2- hydroxynaphthalene-1,4-dione, aromatic aldehydes and heterocyclic or carbocyclic amines in the presence of a catalytic amount of InCl 3 in refluxing water is reported. The structures of the compounds were confirmed by IR, 1H NMR, 13C NMR, and elemental analysis. UV- visible absorption coefficient, maximum wavelength and fluorescence emission wavelength were measured in methanol. The products were fluorescent in solution emitting at green light (546–560 nm). The advantages of this procedure are mild reaction conditions, high yields of products, operational simplicity and easy work-up procedures. The workup of these very clean reactions involves only a filtration and simple washing step with EtOH.

Novel Palladium‐Catalysed Hydroamination of Myrcene and Catalyst Separation by Thermomorphic Solvent Systems

AbstractHydroamination is an elegant and atom economical reaction to convert alkenes into amines. One of the few technical realisations of this reaction is the hydroamination of myrcene to diethylgeranylamine, an important precursor of (−)‐menthol. However, this so‐called “Takasago process” is catalysed by high amounts of alkali metals, especially lithium, which makes it a relatively expensive approach. In the present work, the hydroamination of myrcene with morpholine is catalysed by palladium complexes with bidentate ligands such as bis(diphenylphosphino)butane (DPPB) or bis(2‐diphenylphosphinophenyl) ether (DPEphos). The systematic optimisation of the reaction parameters under single‐phase conditions led to yields of the 1,4‐adducts of higher than 90%. The only side products proved to be the telomers of myrcene, whose formation could be decreased by using appropriate reaction conditions. The method of temperature‐dependent solvent systems was successfully applied to separate the palladium catalyst from the amines with a palladium leaching lower than 1.0%.

Synthesis of Mg–Al–carbonate layered double hydroxide by an atom-economic reaction

A clean method for preparing layered double hydroxides (LDHs) has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reaction. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps (SNAS) method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment.

Ruthenium Hydride Catalyzed Coupling of α,β-Unsaturated Aldehydes with Primary Alcohols

A ruthenium hydride catalyzed cross-coupling between α,β-unsaturated aldehydes and primary alcohols was achieved. This atom-economical reaction leads to the formation of 2-hydroxymethyl ketones in 45-74% yield.

Physicochemical Characterization of Morpholinium Cation Based Protic Ionic Liquids Used As Electrolytes

New protic ionic liquids (PILs) based on the morpholinium, N-methylmorpholinium, and N-ethyl morpholinium cations have been synthesized through a simple and atom-economic neutralization reaction between N-alkyl morpholine and formic acid. Their densities, refractive indices, thermal properties, and electrochemical windows have been measured. The temperature dependence of their dynamic viscosity and ionic conductivity have also been determined. The results allow us to classify them according to a classical Walden diagram and to evaluate their "fragility". In addition, morpholinium based PILs exhibit a large electrochemical window as compared to other protic ionic liquids (up 2.91 V) and possess relatively high ionic conductivities of 10-16.8 mS x cm(-1) at 25 degrees C and 21-29 mS x cm(-1) at 100 degrees C, and a residual conductivity close to 1.0 mS x cm(-1) at -15 degrees C. PIL-water mixtures exhibit high ionic conductivities up to 65 mS x cm(-1) at 25 degrees C and 120 mS x cm(-1) at 100 degrees C for morpholinium formate with water weight fraction w(w) = 0.6. Morpholinium based PILs studied in this work have a low cost and low toxicity, are good ionic liquids, and prove extremely fragile. They have wide applicable perspectives as electrolytes for fuel cell devices, thermal transfer fluids, and acid-catalyzed reaction media as replacements of conventional solvents.